🔧 Altima - Spark Plug Replacement

Your Altima uses four long-life iridium spark plugs, one for each cylinder. Replacement involves removing the ignition coils, cleaning the plug wells, and installing the new plugs without damaging the aluminum cylinder-head threads.

Difficulty Level: Beginner | Estimated Time: 1-1.5 hours

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⚠️ Safety & Precautions

• ⚠️ Let the engine become completely cold before removing the spark plugs.
• 🧤 Wear gloves and safety glasses because debris may be blown from the plug wells.
• 🔑 Keep the ignition switched off and the key away from the vehicle.
• 🔋 Battery disconnection is not required for this repair.
• 🚫 Do not apply anti-seize compound to the new plug threads; it can cause over-tightening.
• 🚫 Never force a spark plug. The cylinder head is aluminum and its threads are easily damaged.

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🔧 Required Tools

You'll need the following tools for this repair:

• 10mm socket
• 3/8-inch-drive ratchet
• 3/8-inch-drive 6-inch extension
• 5/8-inch thin-wall spark plug socket
• 3/8-inch-drive torque wrench rated 10-80 ft-lbs
• 1/4-inch-drive torque wrench rated 20-200 in-lbs
• Compressed-air blow gun rated 90 psi maximum
• Spark plug wire gap gauge marked in 0.1mm increments
• Flashlight rated 100 lumens minimum
• Safety glasses rated ANSI Z87.1
• Nitrile mechanic gloves

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• OEM-spec iridium spark plugs, 1.1mm pre-gap - Qty: 4

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📋 Before You Begin

• 🅿️ Park your Altima on level ground, select Park, and apply the parking brake.
• ❄️ Allow the engine to cool for at least two hours.
• 🧹 Work on one cylinder at a time so the ignition-coil connectors cannot be mixed up.
• 📏 Confirm each new plug is specified for the 2.5L engine. Check for shipping damage with the spark plug gap gauge, but do not bend or adjust an iridium center electrode.
• 📱 No infotainment setting, scan-tool command, programming, or relearn is required.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Remove the engine cover

• Use nitrile mechanic gloves to grasp the plastic engine cover at its mounting points.
• Lift the cover straight upward to release its rubber mounting grommets, then place it safely aside.
• Use the flashlight to locate the four ignition coils arranged in a row on top of the engine.

Step 2: Disconnect the first ignition coil

• Use your gloved fingers to press the locking tab on the first coil’s electrical connector.
• Pull the connector straight from the coil. Pull on the connector body, not its wires.
• Do one cylinder completely before starting another.

Step 3: Remove the ignition coil

• Use the 10mm socket, 6-inch extension, and 3/8-inch-drive ratchet to remove the coil retaining bolt.
• Use your gloved hand to twist the coil gently, then pull it straight upward.
• Inspect the rubber boot for cracking, oil, or burn marks. Oil inside the well can indicate a leaking valve-cover tube seal.

Step 4: Clean the spark plug well

• Put on the safety glasses before using compressed air.
• Use the compressed-air blow gun at no more than 90 psi to clear dirt from the plug well.
• Keep your face away from the well while blowing it clean.
• Use the flashlight to confirm that no loose debris remains.

Step 5: Remove the old spark plug

• Place the 5/8-inch thin-wall spark plug socket on the 6-inch extension and 3/8-inch-drive ratchet.
• Lower the socket straight into the well until it fully seats on the plug.
• Turn counterclockwise slowly until the plug is completely loose, then lift it out with the socket.
• If the plug binds after initially loosening, stop and turn it slightly clockwise before trying again.

Step 6: Inspect the old spark plug

• Use the flashlight to inspect the firing end. Light tan or gray deposits are generally normal.
• Wet fuel, heavy black deposits, oil, or a damaged electrode may indicate another engine problem.
• Keep each removed plug in cylinder order if you need to compare their condition later.

Step 7: Inspect the new spark plug

• Use the spark plug wire gap gauge only to verify an approximately 1.1mm (0.043-inch) gap.
• Do not force a flat blade between the iridium electrodes and do not bend the fine center electrode.
• Use your gloved fingers to confirm the sealing washer is present and the threads are clean and dry.

Step 8: Start the new spark plug by hand

• Insert the new plug into the 5/8-inch thin-wall spark plug socket and attach only the 6-inch extension.
• Lower it straight into the well and turn the extension clockwise by hand for several complete turns.
• If it does not turn easily, remove it and start again. This prevents cross-threading, which means cutting the plug into the threads at the wrong angle.
• A properly started plug turns easily by hand.

Step 9: Tighten the new spark plug

• Attach the 3/8-inch-drive torque wrench to the extension and spark plug socket.
• Tighten the plug smoothly to 19.6 Nm (14 ft-lbs).
• Stop immediately when the torque wrench clicks. Do not tighten it again.
• Do not put anti-seize compound on the spark plug threads.

Step 10: Reinstall the ignition coil

• Use your gloved hand to push the ignition coil straight over the new spark plug until fully seated.
• Start the coil bolt by hand, then tighten it with the 10mm socket and 1/4-inch-drive torque wrench to 7 Nm (62 in-lbs).
• Use your gloved fingers to push the electrical connector onto the coil until its lock clicks.
• Pull lightly on the connector body to verify it is secured.

Step 11: Replace the remaining three plugs

• Repeat Steps 2 through 10 for each remaining cylinder using the same listed tools.
• Use the compressed-air blow gun to clean every plug well before removing its plug.
• Use the torque wrenches to apply 19.6 Nm (14 ft-lbs) to every spark plug and 7 Nm (62 in-lbs) to every coil bolt.

Step 12: Reinstall the engine cover

• Use the flashlight to verify that all four electrical connectors are attached and no tools remain in the engine compartment.
• Use your gloved hands to align the engine-cover mounting points with their rubber grommets.
• Press the cover straight downward over each mounting point until fully seated.

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✅ After Repair

• ✅ Start the engine and let it idle for two to three minutes. It should run smoothly without shaking.
• 👂 Listen for snapping or ticking that could indicate a loose plug or improperly seated ignition coil.
• 🚨 Confirm the malfunction indicator light remains off. If it flashes, shut off the engine immediately and recheck all four coil connectors.
• 🛣️ Take a short, gentle test drive and confirm smooth acceleration.
• 📅 Nissan’s normal-maintenance replacement interval for the original iridium plugs is approximately 105,000 miles, unless operating conditions or plug condition require earlier service.
• 🔍 No scan-tool reset, plug programming, or idle relearn is normally required.

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💰 DIY vs Shop Cost

Shop Cost: ₹7,000-₹13,000 (parts + labor)

DIY Cost: ₹3,500-₹7,000 (parts only)

You Save: ₹3,500-₹6,000 by doing it yourself!

Panipat labor and imported iridium-plug prices vary. This repair takes a shop approximately 0.7-1.0 hour.

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